<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        var weekday = window.prompt("请输入星期:");
        var weekday = parseInt(weekday)
       switch(weekday){
           case 1:
           case 2:
           case 3:
                alert("干煸扁豆6元");
                break;
           case 4:
           case 5:
                alert("蒜茸油麦菜 4元");
                break;
           case 6:
           case 7:
                alert("口水鸡 8元");
                break;
           default:{
                alert("您输入的星期数不正确");
           }
       }
    </script>
</body>
</html>